Proposal: Refactor taxon/location information.

[mycrobe]

Refactor taxon and location information in gene document. (This is motivated by how hard it is to get the species name in gramene search at the moment.)

Currently, taxon information is at the root level, a location subdocument, and an annotation:

{
    "name": "F775_23607",
    "taxon_id": 37682,
    "system_name": "aegilops_tauschii",
    "location": {
        "region": "Scaffold20028",
        "start": 1817,
        "end": 5219,
        "strand": 1,
        "map": "GCA_000347335.1"
    },
    "annotations": {
            "taxonomy": {
                "entries": [
                    {
                        "_id": 37682,
                        "name": "Aegilops tauschii"
                    }
                ],
                "ancestors": [
                    1,
                    2759,
                    3193,
                    …
                ]
            },
            …
        }
    …
}

Instead I propose we should create a taxon subdocument for taxon id and species name, and change the location document, with additional information about map and region pulled in from maps core. The annotations doc should be kept for ancestor information that we use in SOLR.

{
        "name": "F775_23607",
        "taxon": {
            "taxon_id": 37682,
            "name": "Aegilops tauschii"
        },
        "location": {
            "map": {
                "id": "GCA_000347335.1",
                "assembled_length": 0,
                "full_length": 3313764331,
                "genes": 37035,
                "regions": 1,
                "system_name": "aegilops_tauschii"
            },
            "region": {
                "id": "Scaffold20028",
                "idx": 0,
                "length": 3313764331
            },
            "strand": 1,
            "start": 1817,
            "end": 5219
        },
        "annotations": {
            "taxonomy": {
                "ancestors": [
                    1,
                    2759,
                    3193,
                    …
                ]
            },
            …
        },
        …
    },
    …
}